Process of sealing of gas-filled containers



'M. DE NEUMANN PROCESS OF SEALING 0F GAS FILLED CONTAINERS Filed Aug. 4,- 1933 INVENTOR MIHALY DE NEUMANN ATTORNfiYS Patented Oct. 23, 1934 UNITED STATES PATENT OFFICE rnoonss or SEALING or GAS-FILLED CONTAINERS Application August 4, 1938, Serial No. 683,566 In Hungary July 30, 1932 12 Claims.

My invention relates to improvements in or relating to the process of. the airtight or gas-.

tight sealing of gas-filled electric incandescent lamps and the like, the bulbs of which consist of a hollow body or envelope provided with at least one evacuating tube connected to or integral with the bulb, for pumping air or gas out of the bulb, or filling the same with gas, this tube at least being made of such a material, as for example glass, quartz glass, or the like, which shall in the following specification and claims be briefly termed glass-like material, which can be softened or melted by heating, although the body of the bulb may also consist of such glass-like material.

The process according to my invention is of special importance in such cases, when the gas contained in the bulb ofthe lamp has, during the process of sealing, a pressure exceeding the atmospheric pressure, 1. e. the bulb is, during its sealing, subjected to inner pressure exceeding 760 mm. mercury. The present process can be carried out, even in such cases, without undue difficulties'and without employing complicated apparatus. The process of my invention relates particularly to gas-filled electric incandescent lamps, and will be fully explained hereinafter, by way of example in connection with the sealing of such lamps, with due reference to the accompanying drawing, in which Fig. 1 shows the method used heretofore'for the sealing of such lamps, Fig.'

2 the filling tube of glass-like material of a lamp,

provided with an outer sheath, Fig. 3 the manner of heating the sheath and tube, Figs. 4 and 5 the manner of sealing the lamp, i. e. closing the tube, Fig. 6 the tube after being sealed and parted, Fig. '7 another manner of sealing the lam Fgr making the process of my invention readly understood, it is necessary first to state briefly how gas-filled incandescent lamps are usually sealed at present, and have been sealed heretofore, in connection with Fig. 1 of the drawing. This figure shows the glass bulb l of the lamp, provided with the socket 2, and the filling tube 3, also made of glass, connected with the bulb in the usual manner by being fused to the inside of the socket 2 and thereafter blown out. The glass tube 3 is connected, by means of the connecting-piece 4, made of rubber, with the tube 16, leading to the exhausting-pump or the supply of filling gas, not shown. When the bulb 1 has been filled with gas, the tube 3 is heated, in any manner well-known to those skilled in s the art, on its part 5 by gas-flames from the burners 6 and 6' to a temperature above the softening temperature of its material. The bulb 1 being filled with gas at a pressure below the atmospheric pressure, the external pressure of the air readily deforms the softened walls of the tube 3, so that they are pressed and fused together and thus airtightly seal the lamp, thereby effecting the first step of the known process, or the airtight sealing. On further heating the tube, under the influence of the surface tension of the softened glass, the same is parted in two, thereby completing the second step of the known process, the separation.

It is obvious that said process cannot be used for sealing lamps filled with gas at a pressure exceeding that of the atmosphere, because the softenedor molten part of the tube would be blown out by the inner pressure, and the gas thus would escape.

According to my invention, 1 surround the part of the tube which is to be sealed with such a sheath, which is able to bear the inner pressure of the gas filling the bulb, at the temperature necessary for the sealing without materially or disadvantageously altering its shape at the same temperature in consequence of the inner pressure transmitted to it by the softened tube walls, and the heat acting on it at the same time, but readily allows the deformation of the tube necessary for its sealing. Such a sheath must therefore 8 consist of a material, the softening and prefer- 1 ably melting temperature of which lies above the softening and melting temperature of the material of the tube to be sealed.

After having provided the tube with such a sheath, I heat this sheath, preferably on its middle part, in any suitable way to such an extent, that the part of the glass-like tube of the bulb, which is situated inside the sheath is softened. As soon as this has been achieved, I deform the tube in any suitable way, from without or within to close it, so that its walls are fused together, thereby airtightly sealing the bulb. Care must be taken, however, not to heat the sheath to such an extent, that parts ofthe tube being situated in the proximity of its sealing point should be heated high enough to soften, thereby incurring the danger of blow-outs".

The aforementioned sheath may be a hollow, cylindrical body for example, such as a metal 105 tube with thin 'walls, which outwardly fits and is thrust onto the tube to be sealed, and consisting of a suitable metal such as brass. This sheath can also be made on the tube itself by winding on its thin metal foil, or a metallic tissue no such as wire gauze, or metal wire of suitable material and strength, in a suitablenumber of turns or layers. Mica foil or glass texture or glass thread, made of a glass of higher softening and melting temperature than that of the tube to be sealed, and other materials and shapes, such as bands, may also be used. Very good results have been achieved with sheaths made by winding thin brass foils, ofabout 0.008 inch thickness, in several turns about the tube. I have found that the use of sheaths fitting the tube to be sealed tightly is preferable to the use of sheaths having a loose seat on the tube.

To prevent overheating of parts of the tube being near to the part to be sealed, it may sometimes be advantageous to use sheaths made of poorer heat-conducting material than brass, for example of iron. The parts of the tube which are to be protected from overheating may also be protected in other ways, for example by cooling or shielding them in any suitable manner'.

Referring now to Figs. 2 to 6, inclusive, the tube 3 to be sealed is provided, according to my invention, with the sheath 7 of Fig. 2, the lamp then being connected to the pump, pumped out and filled with gas in the usual manner, at any suitable pressure above the atmospheric pressure. Thereafter, the middle part 10 of the tube 3 contained in the sheath 7 is heated by heating the sheath with the gas flames of the gas burners 6 and 6' of Fig. 3 and above and below the point of heating, on the points 11 and 12, the sheath is cooled by streams of air blown on it from the compressed-air nozzles 8, 8' and 9, 9. By thus cooling the sheath, only the middle part 10 of the tube 3 will become heated to its softening temperature, the neighboring parts 11 and 12 will remain cool enough not to soften and therefore they cannot deform to leak and to cause blow-outs. Furthermore, this cooling also prevents the harmful overheating of the lamp socket 2 and of the place of connection of the tube 3 with this socket. It is to be understood, however, that this cooling, although advantageous, is by no means absolutely necessary for successfully carrying out'my invention, because, if the tube 3 does not need to be sealed close to the lamp socket, and therefore may be long enough, such cooling may be dispensed with,

- or, alternatively and even in other cases, a suitable screen, not shown, may be placed between the point of heating and the lamp socket to protect the latter. This screen may be hollow, and be cooled by any suitable cooling medium, such as water or air, streaming through it.

When the middle part 10 of the tube 3 has been heated high enough to soften, the tube is pinched together in order to close or seal it and to separate its lower part from the lamp. This is done with the tools marked 14 and 14' on the Figs. 4 to 6, these tools preferably consisting of suitable steel, and being pressed together in order to seal and to cut the tube 3. The front surfaces of these tools, by pressing the sheath 7 together, join and weld the walls of the tube 3 to provide its airtight sealing, and the sharp edges 15 and 15' of the tools cut the sheath with the tube, so that on the lamp there remains the tube 3 enclosed in the sheath 7, and connected to the gas-supply there remains the lower part 3a of the tube, also sealed, surrounded by the lower part of the sheath 7a. of Figs. 5 and 6. Therefore, now the lamp can be taken off the pumping apparatus by raising it according to Fig. 6. Thereafter, if necessary or desirable, the part of the sheath 7 remaining on the tube 30f the lamp may be removed from this tube in any suitable manner, such as by dissolution with some acid, unwinding, or the like.

I have found that by this proceeding lamps filled with gas at pressures of 5, 10 and even more atmospheres can be sealed without any trouble and blow-out.

The sealing of the tube can also be accomplished according to my invention without deforming and/or cutting the sheath. For this purpose, the present process may be carried out in such a way, that the tube, after having been softened by heating, is closed and sealed by subjecting it to deformation by compression, torsionor both. Re-. ferring to Fig. 7 the tube 3, after having been softened by heating it through the sheath 7 with the gas flames of the burners 6 and 6', is closed by compressing its heated middle part. This is accomplished by subjecting the socket 2, the lower part 3' of the tube, or both to a movement in the direction indicated by the arrows 13 and 13'. Alternatively to or simultaneously with this movement the tube may be subjected to torsion by turning the socket 2, the lower part of the tube 3 or both, in latter case in opposite directions, around the axis of the tube 3. The separation of the lower part 3 of the tube may in this case be effected in any suitable way, for example by again heating the tube and cutting it off together with the shell, by breaking it off in a manner known in itself for cutting glass tubes or rods, when cold, etc.

The heating of the tubeon the point of its sealing may also be effected electrically, for example by using a sheath surrounding the tube in a looplike fashion, and heating this metallic sheath with an electrical current, or by using any other kind of sheath and heating with a separate electrical heating element or device.

I further'wish it to be understood that I do not desire to be limited to the exact ways of proceeding shown-and described, nor to the sealing of lamps filled withgas above atmospheric pressure, for obvious modifications will occur to a person skilled in the art, for example cutting the sheath together with the tube by shearing instead of pinching, cooling the sheath only above or below the point of heating, etc.

The electric incandescent lamps, sealed by the process according to my invention have a tube, the end of which is either fiat, when shorn oil. or bears an edge, when pinched off, or has spiral surface lines or ridges when twisted off, or has the characteristic shining crystalline surface of glass broken cold, and is, furthermore, usually surrounded with the sheath.

I claim:

1. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material 35 connected to the bulb of said lamp, by sealing said tube, which in a combined group of steps consists in applying to at least that part of the tube which is to be sealed a sheath of a substantial materialhaving a higher softening temperature than that of the material of the tube, heating the tube at a point whl'fre it is surrounded by the sheath to its softe ng temperature and thereafter sealing the tube by deforming it on its softened part surrounded by the sheath.

2. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connected to the bulb of said lamp, by sealing said tube, which in a combined group of steps, consists in surrounding part of the tube with a close-fitting sheath made of a substantial material having a higher softening and melting temperature than that of the tube, heating the middle part of said sheath to soften the part of the tube surrounded thereby, and preventing the heatsteps, consist ing of its ends to the softening temperature of the material of the tube, and sealing the tube by deforming it on its softened part.

3.,The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connected to the bulb of said lamp, by sealing said tube, which in a combined group of steps, consists in surrounding part of the tube with-a sheath of substantial material having a higher softening temperature than that of the tube, heating part of the sheath to soften the tube inside the sheath and sealing the tube by compressing it in the direction of its axis.

4. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connected with the bulb of said lamp, by sealing said tube, which in a combined group of in surrounding part of the tube with a metallic sheath of higher softening temperature than that of the tube, heating said sheath to soften the tube inside the sheath and twisting the softened tube.

5. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material conn cted with the bulb of said lamp, by sealing sai tube, which in a combined group of steps, consists in surrounding part of the tube with a sheath of higher softening temperature than that of the tube, heating the sheath to heat the tube inside the sheath to soften the tube and simultaneously compressing and twisting the softened part of the tube.

6. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connected with the bulb of said lamp, by sealing said tube, which in a combined group of steps, consists in surrounding part of the tube with a sheath of higher softening temperature than that of the tube, heating the sheath to soften the tube inside the sheath, and sealing the of the tube by deforming it in- 7. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connected with the bulb of said lamp, by sealing said tube, which in a combined group of steps consists in applying a metallic sheath of higher softening temperature than that of the tube on a part of the tube, heating the sheath to soften "the tube, compressing the sheath together with'the softened part of the tube so as to completely seal said tube, and finally cutting both the sheath and tube after the tube has been sealed.

8. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connected with the bulb of said lamp, by sealing said tube, which in a combined group of steps, consists in forming a metallic sheath of higher softening temperature than that of the tube on a part of the tube by winding on it a pliable metal body, heating said sheath to soften the tube, sealing the tube by deforming its softened part, and thereafter separating the tube.

9. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connected to the bulb of said lamp, by sealing said tube, which in a combined group of steps, consists in applying to the tube a sheath of material having a higher softening temperature than that of the tube, heating the intermediate-part of said sheath with a flame to soften the tube, cooling the end part of said sheath with air, and deforming the softened part of the tube to seal said tube.

10. The process of sealing lamp, provided with a tube connected to the bulb of said lamp, by sealing said tube, which in a combined group of steps, consists in applying to the tube a sheath of material having a higher softening temperature than that of the tube, heating said sheath to soften the tube,

a gas-filled electric sealing said tube by deforming its softened part,

letting the tube cool to stiffen and separating it when cold.

11. The process of sealing a gas-filled electric lamp, provided with a tube of glass-like material connectedto the bulb of said lamp, by sealing said tube, which in a combined group of steps, consists in applying to the tube a metallic sheath of higher softening temperature than that-of the tube, heating said sheath to soften the tube, and sealing the tube by shearing it on its softened part together with the sheath.

12. The process of sealing a la p. rial connected to the bulbof said lamp, by seal? ing said tube, which in a combined group of steps,

gas-filled electric of gas-like material consists in applying to the tube a metallic sheath MIHALY 1m NEUMANN.

said sheath with an electrical cur-. 

